So, what is the exact measurement of....

[GregU]

"the bullet test"? I know a lot of people judge a bore by sticking a cartridge/bullet in the muzzle and declaring that "the bore is good to go"! But I still have to laugh sometimes at some of the ads. One on GB that ended today...."T&E is 3 and the bore passes the bullet test with ease". I've seen several pictures and a lot of different depths that the bullet is sticking into the muzzle. Of course there wasn't a picture with this ad so how did they score this test? The bullet didn't go in to the case mouth? And, it seems to me, if they have a gauge to measure the Throat Erosion, why wouldn't someone have a Muzzle gauge too? I'm just askin....LOL?? Greg

[ebeeby]

Well, the bullet test is a "rule of thumb" sort of thing. Lots of rifles can be shot out through throat erosion long before the bore is gone.
Still, the thing that gets little attention is the condition of the crown. That more often determines a rifle's performance than wear of the bore.

[Allen Humphrey]

Greg,
No argument from me! Ebeeby's description of the intent is correct. In practice, I think it is almost worthless other than spotting a bore that is complete toast. I tried to do a test to see if I could match the results to my gauge. No dice. Totally inconsistent results when using HXP compared to KA, compared to LC. The slightest differences in the Ogive or seating depths changed the results. In my opinion it only shows a difference between "completely gone" and "some life left". Maybe someone else knows a secret to really measure with it??

[Johnny P]

The military had a breech bore gage, but did not issue a muzzle gage. At one time the breech bore gages were fairly common at gun shows, and was a standard measurement as they were all the same. Someone discovered that a .30 M2 round made a good gage for checking for muzzle wear. If approximately 1/4 inch of the M2 round was showing when it was inserted in the muzzle, it had little if any wear. A few enterprising souls came up with a muzzle gage, but if you didn't have one you had nothing to compare it to. Someone with only a couple of rifles really didn't need a muzzle gage, and if he sold a rifle he could pass on the information that it passed the bullet test. If he said it only showed 1/8 inch of bullet, the muzzle had quite a bit of wear.

Several years back when all the Korean M1 Rifles came in they had been cleaned so many times the rifling was usually gone from the muzzle. A local shop bought about 20 of the rifles, and one rifle in particular would take a M2 round almost to the shoulder, and most would touch the cartridge case.

It is much better to have a bullet test than no test at all if the rifle shows considerable use.

This is a M1 Rifle barrel, NOS, showing a bullet test.

http://i40.tinypic.com/1zvbk09.jpg

[George in NH]

This thread points to the issue of how one should care for and maintain the rifles that they value.
Having a "known" M1NM that has clear and sharp rifling to the crown, no pitting and perfect condition chamber and a NINE throat speaks to the proper tools and maintenance by the people who used this rifle before me. For the moment I do not remember the muzzle wear but I believe it is below two. Quite some years ago I was on Viale Range at 600 busily knocking down the X ring; only after that did I become curious about the throat and muzzle readings. That is when I discovered the NINE throat! Accident?? I don't think so, by the by, I was firing LC NM M72. My nineteenth record shot was an X at four........the scorer said "Hit the spotter"......I fired.....and called it center.......the scorer said "Nice shot"......I said why........He said "You hit the spotter"! Last record-X.
George in NH

[chuckindenver]

muzzle wear....effects accuracy more then throught wear.. throught wear is a good sign of use.
M1s will have more muzzle wear then a bolt gun..as they are usually cleaned from that end,
a sectional cleaning rod is hard on that muzzle..